Among various types of heat exchangers, plate-type heat exchangers are used for electric water heaters, industrial equipment, car air-conditioners or the like because their heat exchanging performance is very high.
A plate-type heat exchanger has layered plates for providing paths of heat exchange media, i.e., paths for high- and low-temperature media configured to be adjacent each other so that heat exchange is effected mutually by virtue of the temperature difference between the media flowing through these paths of the high- and low-temperature media.
For example, in Patent Document 1, plates having corrugated portions for forming flow paths are layered and joined by various joining methods (fastening with a gasket and screw, welding, brazing) to obtain a structure in which high-temperature flow paths and low-temperature flow paths are alternated. Meanwhile, in view of an improved durability of a heat exchanger itself, stainless steel sheets, which have excellent corrosion resistance, are used as metal plate materials.
Further, for small-to-medium sized heat exchangers, joining operations are often performed by brazing in view of pressure resistance.
Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2010-85094